Also, mind the LotAmount value in your asset list.

You can set the Amount variable instead of the Lots value to get the intended effect.

For example, suppose you want to buy 0.1 BTC/USD. If LotAmount is 0.001 and you set the Amount variable to 0.1 in your script, then it will set Lots to the correct value of 100. 100 x 0.001 BTC/USD = 0.1 BTC/USD.